execve updates for v6.18-rc1

- binfmt_elf: preserve original ELF e_flags for core dumps (Svetlana
   Parfenova)
 
 - exec: Fix incorrect type for ret (Xichao Zhao)
 
 - binfmt_elf: Replace offsetof() with struct_size() in fill_note_info()
   (Xichao Zhao)
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Merge tag 'execve-v6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve updates from Kees Cook:

 - binfmt_elf: preserve original ELF e_flags for core dumps (Svetlana
   Parfenova)

 - exec: Fix incorrect type for ret (Xichao Zhao)

 - binfmt_elf: Replace offsetof() with struct_size() in fill_note_info()
   (Xichao Zhao)

* tag 'execve-v6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  binfmt_elf: preserve original ELF e_flags for core dumps
  binfmt_elf: Replace offsetof() with struct_size() in fill_note_info()
  exec: Fix incorrect type for ret

arch/riscv/Kconfig

@@ -28,6 +28,7 @@ config RISCV
 	select ARCH_HAS_DEBUG_VIRTUAL if MMU
 	select ARCH_HAS_DEBUG_VM_PGTABLE
 	select ARCH_HAS_DEBUG_WX
+	select ARCH_HAS_ELF_CORE_EFLAGS
 	select ARCH_HAS_FAST_MULTIPLIER
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL

fs/Kconfig.binfmt

@@ -184,4 +184,13 @@ config EXEC_KUNIT_TEST
 	  This builds the exec KUnit tests, which tests boundary conditions
 	  of various aspects of the exec internals.
 
+config ARCH_HAS_ELF_CORE_EFLAGS
+	bool
+	depends on BINFMT_ELF && ELF_CORE
+	default n
+	help
+	  Select this option if the architecture makes use of the e_flags
+	  field in the ELF header to store ABI or other architecture-specific
+	  information that should be preserved in core dumps.
+
 endmenu

fs/binfmt_elf.c

@@ -103,6 +103,21 @@ static struct linux_binfmt elf_format = {
 
 #define BAD_ADDR(x) (unlikely((unsigned long)(x) >= TASK_SIZE))
 
+static inline void elf_coredump_set_mm_eflags(struct mm_struct *mm, u32 flags)
+{
+#ifdef CONFIG_ARCH_HAS_ELF_CORE_EFLAGS
+	mm->saved_e_flags = flags;
+#endif
+}
+
+static inline u32 elf_coredump_get_mm_eflags(struct mm_struct *mm, u32 flags)
+{
+#ifdef CONFIG_ARCH_HAS_ELF_CORE_EFLAGS
+	flags = mm->saved_e_flags;
+#endif
+	return flags;
+}
+
 /*
  * We need to explicitly zero any trailing portion of the page that follows
  * p_filesz when it ends before the page ends (e.g. bss), otherwise this
@@ -1290,6 +1305,8 @@ static int load_elf_binary(struct linux_binprm *bprm)
 	mm->end_data = end_data;
 	mm->start_stack = bprm->p;
 
+	elf_coredump_set_mm_eflags(mm, elf_ex->e_flags);
+
 	/**
 	 * DOC: "brk" handling
 	 *
@@ -1804,6 +1821,8 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
 	struct elf_thread_core_info *t;
 	struct elf_prpsinfo *psinfo;
 	struct core_thread *ct;
+	u16 machine;
+	u32 flags;
 
 	psinfo = kmalloc(sizeof(*psinfo), GFP_KERNEL);
 	if (!psinfo)
@@ -1831,30 +1850,37 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
 		return 0;
 	}
 
-	/*
-	 * Initialize the ELF file header.
-	 */
-	fill_elf_header(elf, phdrs,
-			view->e_machine, view->e_flags);
+	machine = view->e_machine;
+	flags = view->e_flags;
 #else
 	view = NULL;
 	info->thread_notes = 2;
-	fill_elf_header(elf, phdrs, ELF_ARCH, ELF_CORE_EFLAGS);
+	machine = ELF_ARCH;
+	flags = ELF_CORE_EFLAGS;
 #endif
 
+	/*
+	 * Override ELF e_flags with value taken from process,
+	 * if arch needs that.
+	 */
+	flags = elf_coredump_get_mm_eflags(dump_task->mm, flags);
+
+	/*
+	 * Initialize the ELF file header.
+	 */
+	fill_elf_header(elf, phdrs, machine, flags);
+
 	/*
 	 * Allocate a structure for each thread.
 	 */
-	info->thread = kzalloc(offsetof(struct elf_thread_core_info,
-				     notes[info->thread_notes]),
-			    GFP_KERNEL);
+	info->thread = kzalloc(struct_size(info->thread, notes, info->thread_notes),
+			       GFP_KERNEL);
 	if (unlikely(!info->thread))
 		return 0;
 
 	info->thread->task = dump_task;
 	for (ct = dump_task->signal->core_state->dumper.next; ct; ct = ct->next) {
-		t = kzalloc(offsetof(struct elf_thread_core_info,
-				     notes[info->thread_notes]),
+		t = kzalloc(struct_size(t, notes, info->thread_notes),
 			    GFP_KERNEL);
 		if (unlikely(!t))
 			return 0;

fs/exec.c

@@ -599,7 +599,7 @@ int setup_arg_pages(struct linux_binprm *bprm,
 		    unsigned long stack_top,
 		    int executable_stack)
 {
-	unsigned long ret;
+	int ret;
 	unsigned long stack_shift;
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma = bprm->vma;

include/linux/mm_types.h

@@ -1107,6 +1107,11 @@ struct mm_struct {
 
 		unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
 
+#ifdef CONFIG_ARCH_HAS_ELF_CORE_EFLAGS
+		/* the ABI-related flags from the ELF header. Used for core dump */
+		unsigned long saved_e_flags;
+#endif
+
 		struct percpu_counter rss_stat[NR_MM_COUNTERS];
 
 		struct linux_binfmt *binfmt;